AVIT 428 TEST 3 A320 QUESTIONS & ANSWERS
Major Componets of hydraulic system - Answer -The hydraulic system is designed to
provide primary and redundant sources of hydraulic power to operate major
components such as: flight controls, flaps and slats, landing gear, cargo doors, and the
emergency generator.
The hydraulic system is made up of three separate and independent systems: - Answer
-The Green system
The Blue system
The Yellow system
Normal Pressure? - Answer -Normal system pressure is provided by engine-driven
hydraulic pumps at approximately 3,000 psi.
Hydraulic Backups - Answer -Additionally, backup pressure can be provided by:
Electrically-driven hydraulic pumps
A Power Transfer Unit (PTU)
A Ram Air Turbine (RAT)
A hand pump
Hydraulic fluid is routed to each component through independent lines and is then
returned back to the hydraulic reservoir.
Fire shutoff valves installed upstream of each engine-driven pump prevents hydraulic
fluid from flowing to the pump in the event of an engine fire.
Each system has an accumulator installed which helps maintain a constant pressure
during transient demands.
The hydraulic system is controlled by pbs located on the overhead HYD panel.
However some pbs on the overhead FIRE panel have secondary control over certain
hydraulic components.
The HYD page displays hydraulic system information such as: - Answer -Reservoirs
Fire shutoff valves
Engine-driven pumps
Electric pumps
Individual system pressure information
The engine identification numbers, 1 and 2, indicate which components are controlled
by that engine.
When the systems are operating normally, the system labels are white and the triangle
and digital readout of system pressure is green.
,When the systems are not pressurized prior to engine start, or in this example, when
pressure drops below a preset threshold, the information changes to amber.
The E/WD will alert you to hydraulic system non-normals.
Where are hydraulic abnormals shown? - Answer -The E/WD will alert you to hydraulic
system non-normals.
Green System - Answer -The Green hydraulic system is used to power items such as:
Nosewheel steering
Landing Gear
Slats and Flaps
Thrust reverser for engine #1
The normal braking system
Flight control components
Normal system pressure comes from a single engine hydraulic pump powered by
engine #1.
If hydraulic pressure from the engine is unavailable, backup pressure can be provided
by the PTU.
Yellow System - Answer -Flaps
Thrust reverser for engine #2
Alternate/Parking Brake
Flight control components
Cargo doors
The Yellow hydraulic system can be pressurized by either an engine driven hydraulic
pump or an electrically driven hydraulic pump.
If these hydraulic pumps are unavailable, pressure can be provided by the PTU.
A hand pump is also available to open the cargo doors when the aircraft is unpowered
on the ground.
Blue System - Answer -Emergency generator
Slats
Flight control components
The Blue hydraulic system is pressurized by a single electric pump when the engines
are running.
If the electric pump fails, a Ram Air Turbine (RAT) can be deployed to provide pressure.
Reservoirs - Answer -Each hydraulic system is equipped with a reservoir for fluid
storage and recirculation.
To prevent pump cavitation, the reservoir is automatically pressurized by the pneumatic
system.
Let's take a closer look at the HYD page for the reservoir indications.
Reservoir quantity is indicated by a vertical line with a caret.
,A normal quantity is indicated when the caret is within the green box.
If the pointer indicates below the green box, the system requires servicing.
Low fluid level is indicated by an amber box.
If fluid level is below this preset limit, the indications turn amber, and a caution message
appears on the E/WD.
If a reservoir overheats (OVHT) or low air pressure (LO AIR PRESS) is detected, these
indications appear next to the respective reservoir.
Fire Valves - Answer -A fire shutoff valve is installed upstream of the engine driven
pumps in the Green and Yellow systems.
These valves stop hydraulic fluid from flowing to the engines if an engine fire occurs,
and are controlled by the ENG FIRE pbs.
The Green system is controlled by the ENG 1 FIRE pb and the Yellow system is
controlled by the ENG 2 FIRE pb.
When a fire shutoff valve is in its normal open position, it is displayed in-line green.
To see a fire valve close, press the ENG 2 FIRE pb.
When the fire valve is fully closed it changes to cross line amber.
Looking more closely at the HYD page, it appears that with the fire valve closed,
hydraulic fluid is not available to pressurize the system.
However, that is not the case.
Using the Yellow system as an example, when the fire valve closes, this only prevents
hydraulic fluid from flowing to the engine-driven pump.
As you can see, the Yellow electric pump or the PTU still has fluid available, allowing for
continued pressurization of the Yellow system.
Engine Driven Pump - Answer -Because the engine driven hyd pump is connected to
the accessory gearbox the pump operates whenever the engine is running
During normal operation the pbs are in the on (lights out) configuration, which allows for
pump operation when the engines are running.
The HYD page is indicating the pumps are operating normally.
When the pb is selected to OFF, the engine driven pump is depressurized.
OFF appears in the pb and the pump symbol changes to an amber dash.
If pump output is low, the FAULT light illuminates in the ENG pb and the symbol
changes to LO.
A FAULT light illuminating in either engine hydraulic pump pb can indicate any of the
following:
The engine driven hydraulic pump is producing low output pressure
The respective hydraulic reservoir is at a low level
The reservoir is overheating
The reservoir has low air pressure
Electrically Driven Pumps - Answer -There are two electric pumps: one for the Yellow
system and one for the Blue system.
, Yellow Electric Pump
The Yellow electric pump is a backup source of pressure for the Yellow system.
The Yellow electric pump must be manually selected; there is no automatic function if
engine pump pressure is lost.
You can manually activate this pump using the YELLOW ELEC PUMP pb on the HYD
panel.
The YELLOW ELEC PUMP pb is normally in the (off) lights out position.
This is the normal ECAM display when the Yellow electric pump is not operating.
Select the YELLOW ELEC pb pump ON.
Note the normal pressure indication of 3,000 psi.
Now turn the Yellow electric pump off.
The Yellow electric pump also has an automatic function.
Prior to engine start, when a cargo door selector is placed in either the open or close
position, the pump activates.
In this case, the Yellow system will only power:
The cargo doors
The alternate brake system
The engine two reverser blocker doors
When this automatic operation occurs the ON light does not illuminate in the pb.
On the HYD page you will see the pressure output of the electric pump.
Blue Electric Pump
The other electric hydraulic pump pressurizes the BLUE hydraulic system.
Since it is the primary pressure source, this electric pump is displayed on the HYD page
in the same manner as the two engine driven pumps.
You can control this pump using the guarded BLUE ELEC PUMP pb.
This pb is normally left in the AUTO (lights out) position, allowing for automatic
activation.
On the ground, as long as the aircraft has normal AC power, the BLUE electric pump
comes on line automatically when at least one engine is running.
In flight, if AC power is available, this pump operates continuously, even if both engines
are shut down.
Turn off the blue electric pump.
When this pb is selected to off, the OFF light illuminate
PTU - Answer -PTU performs a momentary self test during the second engine start
A backup source of pressure for the Green and Yellow systems is the Power Transfer
Unit, or PTU.
The PTU is a hydraulically powered motor that allows the Yellow system to pressurize
the Green system or the Green system to pressurize the Yellow system.
The PTU is controlled by the PTU pb on the overhead HYD panel.
The PTU activates automatically when the PTU pb is in AUTO (lights out) and a
differential pressure greater than 500 psi is sensed between the Yellow and Green
hydraulic systems.
The HYD page indicates the status of PTU operation.
In this example, the PTU is shown in its standby mode.
Let's see what happens to the PTU indication when the Yellow system is shutdown.
Major Componets of hydraulic system - Answer -The hydraulic system is designed to
provide primary and redundant sources of hydraulic power to operate major
components such as: flight controls, flaps and slats, landing gear, cargo doors, and the
emergency generator.
The hydraulic system is made up of three separate and independent systems: - Answer
-The Green system
The Blue system
The Yellow system
Normal Pressure? - Answer -Normal system pressure is provided by engine-driven
hydraulic pumps at approximately 3,000 psi.
Hydraulic Backups - Answer -Additionally, backup pressure can be provided by:
Electrically-driven hydraulic pumps
A Power Transfer Unit (PTU)
A Ram Air Turbine (RAT)
A hand pump
Hydraulic fluid is routed to each component through independent lines and is then
returned back to the hydraulic reservoir.
Fire shutoff valves installed upstream of each engine-driven pump prevents hydraulic
fluid from flowing to the pump in the event of an engine fire.
Each system has an accumulator installed which helps maintain a constant pressure
during transient demands.
The hydraulic system is controlled by pbs located on the overhead HYD panel.
However some pbs on the overhead FIRE panel have secondary control over certain
hydraulic components.
The HYD page displays hydraulic system information such as: - Answer -Reservoirs
Fire shutoff valves
Engine-driven pumps
Electric pumps
Individual system pressure information
The engine identification numbers, 1 and 2, indicate which components are controlled
by that engine.
When the systems are operating normally, the system labels are white and the triangle
and digital readout of system pressure is green.
,When the systems are not pressurized prior to engine start, or in this example, when
pressure drops below a preset threshold, the information changes to amber.
The E/WD will alert you to hydraulic system non-normals.
Where are hydraulic abnormals shown? - Answer -The E/WD will alert you to hydraulic
system non-normals.
Green System - Answer -The Green hydraulic system is used to power items such as:
Nosewheel steering
Landing Gear
Slats and Flaps
Thrust reverser for engine #1
The normal braking system
Flight control components
Normal system pressure comes from a single engine hydraulic pump powered by
engine #1.
If hydraulic pressure from the engine is unavailable, backup pressure can be provided
by the PTU.
Yellow System - Answer -Flaps
Thrust reverser for engine #2
Alternate/Parking Brake
Flight control components
Cargo doors
The Yellow hydraulic system can be pressurized by either an engine driven hydraulic
pump or an electrically driven hydraulic pump.
If these hydraulic pumps are unavailable, pressure can be provided by the PTU.
A hand pump is also available to open the cargo doors when the aircraft is unpowered
on the ground.
Blue System - Answer -Emergency generator
Slats
Flight control components
The Blue hydraulic system is pressurized by a single electric pump when the engines
are running.
If the electric pump fails, a Ram Air Turbine (RAT) can be deployed to provide pressure.
Reservoirs - Answer -Each hydraulic system is equipped with a reservoir for fluid
storage and recirculation.
To prevent pump cavitation, the reservoir is automatically pressurized by the pneumatic
system.
Let's take a closer look at the HYD page for the reservoir indications.
Reservoir quantity is indicated by a vertical line with a caret.
,A normal quantity is indicated when the caret is within the green box.
If the pointer indicates below the green box, the system requires servicing.
Low fluid level is indicated by an amber box.
If fluid level is below this preset limit, the indications turn amber, and a caution message
appears on the E/WD.
If a reservoir overheats (OVHT) or low air pressure (LO AIR PRESS) is detected, these
indications appear next to the respective reservoir.
Fire Valves - Answer -A fire shutoff valve is installed upstream of the engine driven
pumps in the Green and Yellow systems.
These valves stop hydraulic fluid from flowing to the engines if an engine fire occurs,
and are controlled by the ENG FIRE pbs.
The Green system is controlled by the ENG 1 FIRE pb and the Yellow system is
controlled by the ENG 2 FIRE pb.
When a fire shutoff valve is in its normal open position, it is displayed in-line green.
To see a fire valve close, press the ENG 2 FIRE pb.
When the fire valve is fully closed it changes to cross line amber.
Looking more closely at the HYD page, it appears that with the fire valve closed,
hydraulic fluid is not available to pressurize the system.
However, that is not the case.
Using the Yellow system as an example, when the fire valve closes, this only prevents
hydraulic fluid from flowing to the engine-driven pump.
As you can see, the Yellow electric pump or the PTU still has fluid available, allowing for
continued pressurization of the Yellow system.
Engine Driven Pump - Answer -Because the engine driven hyd pump is connected to
the accessory gearbox the pump operates whenever the engine is running
During normal operation the pbs are in the on (lights out) configuration, which allows for
pump operation when the engines are running.
The HYD page is indicating the pumps are operating normally.
When the pb is selected to OFF, the engine driven pump is depressurized.
OFF appears in the pb and the pump symbol changes to an amber dash.
If pump output is low, the FAULT light illuminates in the ENG pb and the symbol
changes to LO.
A FAULT light illuminating in either engine hydraulic pump pb can indicate any of the
following:
The engine driven hydraulic pump is producing low output pressure
The respective hydraulic reservoir is at a low level
The reservoir is overheating
The reservoir has low air pressure
Electrically Driven Pumps - Answer -There are two electric pumps: one for the Yellow
system and one for the Blue system.
, Yellow Electric Pump
The Yellow electric pump is a backup source of pressure for the Yellow system.
The Yellow electric pump must be manually selected; there is no automatic function if
engine pump pressure is lost.
You can manually activate this pump using the YELLOW ELEC PUMP pb on the HYD
panel.
The YELLOW ELEC PUMP pb is normally in the (off) lights out position.
This is the normal ECAM display when the Yellow electric pump is not operating.
Select the YELLOW ELEC pb pump ON.
Note the normal pressure indication of 3,000 psi.
Now turn the Yellow electric pump off.
The Yellow electric pump also has an automatic function.
Prior to engine start, when a cargo door selector is placed in either the open or close
position, the pump activates.
In this case, the Yellow system will only power:
The cargo doors
The alternate brake system
The engine two reverser blocker doors
When this automatic operation occurs the ON light does not illuminate in the pb.
On the HYD page you will see the pressure output of the electric pump.
Blue Electric Pump
The other electric hydraulic pump pressurizes the BLUE hydraulic system.
Since it is the primary pressure source, this electric pump is displayed on the HYD page
in the same manner as the two engine driven pumps.
You can control this pump using the guarded BLUE ELEC PUMP pb.
This pb is normally left in the AUTO (lights out) position, allowing for automatic
activation.
On the ground, as long as the aircraft has normal AC power, the BLUE electric pump
comes on line automatically when at least one engine is running.
In flight, if AC power is available, this pump operates continuously, even if both engines
are shut down.
Turn off the blue electric pump.
When this pb is selected to off, the OFF light illuminate
PTU - Answer -PTU performs a momentary self test during the second engine start
A backup source of pressure for the Green and Yellow systems is the Power Transfer
Unit, or PTU.
The PTU is a hydraulically powered motor that allows the Yellow system to pressurize
the Green system or the Green system to pressurize the Yellow system.
The PTU is controlled by the PTU pb on the overhead HYD panel.
The PTU activates automatically when the PTU pb is in AUTO (lights out) and a
differential pressure greater than 500 psi is sensed between the Yellow and Green
hydraulic systems.
The HYD page indicates the status of PTU operation.
In this example, the PTU is shown in its standby mode.
Let's see what happens to the PTU indication when the Yellow system is shutdown.
